The infant domestic pig, one day to eight weeks of age, is currently being researched as a possible suitable animal model in whic to study a Sudden Infant Death like syndrome. The mechanism(s) involved in the respiratory and cardiovascular reflex responses to normally non-life threatening stimuli which often result in death are being researched. Reflex induced apnea leading to bradycardia, arrhythmias, hypotension and death has resulted from simple postural alteration (lateral to supine), slight head and neck flexion producing snoring, laryngeal mainpulation or temporary nasal occlusion (30-45 sec.). Quantitative fluorometric analysis for biogenic amines within specific areas of the central nervous system have been perfomed. The levels in the cardiorespiratory control centers medulla and pons) are approximately half the values reported for other higher mammals. The principal investigator believes that afferent impulse stimulating the central regulatory centers result in efferent responses which are immature, inappropriate or insufficient resulting in the life threatening apnea. Attempts will be made to manipulate central amine levels pharmacologically to determine whether the condition seen in infant pigs may be aggravated or alleviated in this manner. Specific peripheral autonomic blocking drugs will also be employed to delineate the route efferent impulses travel in the production of apnea leading to death.